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CHAPTER 10 SEDIMENTARY BASINS - Coggle Diagram
CHAPTER 10 SEDIMENTARY BASINS
This chapter describes the sedimentary basins in which the last acts of the great saga take place.
Sediment Supply and Accommodation Space
In marine environments, tides, wind and wave-generated currents can be so strong that sediments can never accumulate to sea level, but are constantly redistributed across the shelf or into deeper water.
In a closed continental basin, the concept of accommodation space is further complicated. In lake basins, the accommodation space can still be defined as the interval between the lake bed and the surface.
The rate at which the accommodation space fills is a function of several variables in the watershed and in the drainage catchment area. Variables within the basin include the environment and its energy level. The ability of wind, wave, and tidal currents to transport, segregate, and deposit sediment.
For sediments to accumulate in a marine basin there must be a vertical interval, called the accommodation space, between sea level and the seafloor, the top of the accumulation (Jervey, 1988).
Basin-Forming Mechanisms
The accommodation space can be created by three tectonic processes (Stoneley, 1969).
Subsidence can occur when subcosmic displacement of the mantle causes downward creep and compressional deformation of the crust. This occurs mainly in what are called subduction zones, linear features that are the site of extensive sedimentation.
Sedimentation can also occur on a large scale when changes in the mantle cause crustal subsidence and subsidence. This process is responsible for intracratonic basins. Conversely, these changes can cause crustal bulging. Thick volcanic and sedimentary sequences can form in ridge basins.
Thick sedimentary sequences can form in which the weight of the sediments themselves causes an isostatic depression of the crust. The most likely place for such a process is the continental margin, where an entire ocean basin waits to be filled. to be refilled. Sedimentation at the foot of the continental slope can cause an isostatic crustal depression (Drake et al., 1968).
Basic Concepts and Terminology
Sedimentary rocks cover a large part of the Earth's surface, including about 75% of the land areas. However, sedimentary rocks account for only 5% of the lithosphere (data from Pettijohn, 1957, p. 7). From this it follows that sedimentary rocks cover the earth only as a thin and shallow.
Basins are of three types: topographic, structural and sedimentary.
Sedimentary basins classified and described
Sedimentary basin classification
Crystal Sag Basins
It is an essentially saucer-shaped area of sedimentary rocks. Therefore, it is underlined in plan view. The strata submerge and thicken centripetally towards the center of the basin
Intracratonic Crustal Sag Basins
Intracratonic basins are the classic type of sedimentary basin. Modern intracratonic sag basins include the Hudson Bay and the Baltic Sea, which lie on the Canadian and Scandinavian shields, respectively.
Epicratonic Basins and Continental Margin Downwarps
Morphologically they range from embayments that plunge toward the ocean, to laterally extensive continental margin downwarps
Basins Caused by Plate Convergence
several types of basin are related to zones of crustal subduction at compressive plate boundaries
Basins Caused by Plate Divergence
They are of considerable economic importance as sources of hydrocarbons, evaporites, and metals.
Intercratonic Riffs
Intracontinental Rift Basins
Basin evolution, metallogeny and the petroleum system
Having reviewed the different types of basins, it is appropriate to conclude with an analysis of how they are genetically related in time and space. It is now apparent that many basins undergo a regular sequence of structural phases.
Recognition of this sequence of events and facies has important implications for understanding metallogenesis and petroleum generation, migration and trapping.